OBJECTIVE: The aim of this study was to compare estimates of Pap smear and mammogram screening obtained from household and telephone surveys in women living in São Paulo in 2008, according to sociodemographic characteristics, and to measure the differences observed from those estimates. METHODS: The study compared data from ISA - Capital 2008, a household survey conducted in São Paulo by Universidade de São Paulo (USP), Universidade Estadual de Campinas (UNICAMP) and the State Health Department with support from the Municipal Health Department, and VIGITEL - São Paulo, a telephone-based Surveillance of Risk and Protective Factors for Chronic Diseases. Estimates of Pap smear and mammography, as well as their realization in the year prior to the interview, were compared according to type of survey (household/telephone) by Poisson regression adjusted for age and education. RESULTS: There were no statistically significant differences between the estimates obtained by VIGITEL and ISA - Capital as to the prevalence of mammography in the year prior to the interview. However, global estimates of the Pap smear at least once in life and in the past year, as well as mammograghy at least once in life, show statistically significant differences, with higher prevalence rates of coverage among those interviewed by telephone. CONCLUSION: The results indicate a tendency to overestimate coverage of mammography and Pap smear in the telephone survey data, which indicates the need for new studies that also contribute to a better understanding of the differences observed by different types of surveys.